Montgomery and Peck (1992) describe the use of regression model to relate the amount of time required by route salesman (driver) to service a soft-drink vending machine to the number of case stocked in the machine and the distance from the service vehicle to the machine location. This model was used for route design, scheduling, and vehicle dispatching. Table 10-2 present 25 observations on delivery time taken from the same study described by Montgomery and Peck. (Note that this is and expansion of the data set used in Example 9-10, where only the number of case stocked was used as regressor.)